Mine sterilization by means of a deliquescent additive

ABSTRACT

SELF-STERILIZATION CAPABILITY IS IMPARTED TO A CHEMICALLY ORIENTED MINE BY THE INCORPORATION INTO THE ACTIVE EXPLOSIVE OF A MATERIAL WHICH IS HYGROSCOPIC AND DELIQUESCENT. THE LATTER MATERIAL ABSORBS MOISTURE FROM THE ATMOSPHERE AND DELIQUESCES INTO AN AQUEOUS SOLUTION WHICH REACTS WITH THE ACTIVE EXPLOSIVE RENDERING IT LESS SENSITIVE AND ULTIMATELY STERILIZED AND SAFE TO HANDLE.

United States Patent fifice 3,718,513 Patented Feb. 27, 1973 3,718,513MINE STERILIZATION BY MEANS OF A DELIQUESCENT ADDITIVE Maurice Baer andJoseph H. Severini, Morris, N.J., as-

signors to the United States of America as represented by the Secretaryof the Army No Drawing. Filed Jan. 25, 1971, Ser. No. 109,629

Int. Cl. C06c 1/00 US. Cl. 149-24 13 Claims ABSTRACT OF THE DISCLOSURESelf-sterilization capability is imparted to a chemically oriented mineby the incorporation into the active explosive of a material which ishygroscopic and deliquescent. The latter material absorbs moisture fromthe atmosphere and deliquesces into an aqueous solution which reactswith the active explosive rendering it less sensitive and ultimatelysterilized and safe to handle.

The invention described herein may be manufactured, used and licensed byor for the Government for governmental purposes without the payment touse of any royalties thereon.

Broadly, this invention relates to the sterilization of a chemicallyoriented mine.

More particularly, this invention relates to a chemically oriented minehaving means for use in the sterilization of such mine over apredetermined period of time.

The success of a military offensive within a specified zone or sector ofa battlefield requires a relatively high mobility and this in the lastanalysis dictates some type of movement by the infantry within the zonein issue. It is therefore a military requirement of the defending forcesto impede or hinder this movement thereby retarding the full use of theresources of the enemy and hopefully the success of their mission. Inmodern times, this is accomplished within a specified zone or sector bythe mass sowing of items of destruction such as mines and the like.

However, after a time, in order for the defending forces to have accessand mobility of their own within the sector, there must be someprovision for the deactivation of such items of destruction in acomparatively safe manner. In the past, there were numerous mechanicaladaptations \placed on mines for the express purpose of sterilizationbut none of these expedients were readily acceptable due to a loss ofreliability of the mine, clumsiness of construction of the sterilizingdevice itself, and/or prohibitive cost. In particular, these mechanicaladaptations were not readily adaptable to the pressure-sensitivelow-cost chemically oriented mines of the lead azide variety.

The subject invention answers the needs of the art as heretoforedescribed with special emphasis on the sterilization of a chemicallyoriented mine with facility over a predetermined duration of time.

It is therefore an object of this invention to provide an improved meansfor the sterilization of a chemically oriented mine.

Another object is to :provide a chemically oriented mine adapted withmeans for desensitization and subsequent sterilization over apredetermined period of time.

A further object is to provide a pressure-sensitive chemically orientedmine of the lead azide variety with means for use in theself-sterilization of said mines over a predetermined period of time.

A still further object is to provide the aforesaid means having lowfabrication and maintenance cost and being operative over a wide varietyof service conditions in many different chemically oriented mines.

Other objects and many of the attendant advantages of this inventionwill become better understood upon a reading of the following detailedspecification wherein:

This invention broadly encompasses the desensitization and ultimatesterilization of a chemically oriented mine containing a primaryexplosive, such as for example lead azide and other metallic azides andlead styphnate, by the incorporation into such explosive material of ahygroscopic additive which will ultimately deliquesce to solvate andreact with such explosive material, thereby rendering it substantiallyinactive and ultimately inert over a predetermined period of time.

More specifically, this invention essentially encompasses theincorporation of an additive into the primary explosive ingredients of amine of the lead azide variety which absorbs moisture from theatmosphere and deliquesces, thereby resulting in a chemical solutionwhich reacts with such explosive ingredients to render them sterilizedand safe to handle.

This invention is particularly advantageous with respect to a chemicalor chemically oriented mine of the lead azide variety which is used foranti-personnel action.

The materials or additives which may be utilized to desensitize andultimately sterilize the primary explosive ingredients of a mine includecalcium chloride, lithium chloride, magnesium chloride, sodium sulfatesodium hydroxide, and potassium hydroxide.

The additive in the substantially anhydrous form is placed, either asloose powder or in pellet form, into a housing or bag which is waterrepellent but permeable to water vapor. Water vapor is extracted fromthe atmosphere by the hygroscopic additive, which deliquesces, therebyspreading a solution of the additive throughout the explosive mixture inthe bag rendering it sub stantially less sensitive to impact. Lithiumchloride is especially useful for this purpose due to its ability todeliquesce at relatively low humidity. Furthermore, the additive insolution form will react with the primary explosive component, therebysterilizing the mine. The hygroscopic additives of this invention arealso effective for desensitizing organic azides; e.g., cyanurictriazide. Thus, anti-personnel mines containing an organic azide as theprimary explosive can be desensitized by the aqueous hygroscopicadditive to such a degree that the mine is no longer sensitive topersonnel action. However, owing to their poor solubility in aqueousmedia, such organic azides will react slowly with the aqueoushygroscopic additive and ultimate complete sterilization of the minewill be extremely slow if not impractical.

To insure further sterilization of the explosive ingredients, thetetrasodium salt of ethylenediamine teraacetic acid is added in powderform to the lithium chloride additive. In this manner, the metal, suchas lead, is extracted from the primary explosive material by theaforementioned salt of tetraacetic acid thereby insuring sterilization.

The rate of absorption and deliquescence is based on the surface areaexposed to the ambient air which is also a function of the particle sizedistribution of the additive. A preferred embodiment in pellet formwhich has been found to be highly satisfactory is set forth in Example Iwhich follows:

EXAMPLE Physical characteristics:

(a) Wt. of pellet-3.000 gramsi0.362 gram, max. (b) Dimension:

Diameter-3401.007 in. Thickness-.220 in. max. (c) Density-1.64 gm./cc.min. (d) Composition:

Anhydrous lithium chloride-6.62:3% The tetra sodium salt ofethylenediaminetetraacetic acid33.1i3% Graphite-0.7 max.

In operation-When the mine is exposed to the ambient atmosphere, theanhydrous lithium chloride component of the pellet extracts moisturefrom the atmosphere. Over a period of time, the pellet extracts enoughwater to cause itself to deliquesce. The resulting aqueous solutionchemically reacts with the primary explosive; e.g., lead azide in themine thereby sterilizing the same.

The composition of the aforedescribed pellet is such that the activelife of the mine is predictable. Furthermore, the tolerances withrespect to dimensions, density and composition of the pellet are suchthat the actual sterilization times will fall within the predictedsterilization times for a given set of temperature and humidityconditions.

The invention as heretofore described provides an entirely newcapability for the military. Previously, mines once emplaced were apermanent threat to future movement of friendly forces attempting topass through an area which they themselves had mined. This invention hasprovided a new capability in mines and a definite tactical advantage tosuch friendly forces. The mines which have been adapted with the meansof this invention will automatically become sterilized after a knownperiod of time and after that will not impede the mobility of suchforces.

We claim:

1. In a pressure-sensitive chemical mine containing a primary explosiveselected from the group consisting of metal azides and lead styphnate,the combination therewith of a deliquescent additive selected from thegroup consisting of alkali metal and alkaline earth metal chlorides,hydroxides, and sulfates, said deliquescent additive forming an aqueoussolution reactive with said primary explosive, thereby desensitizing andsterilizing said mine.

2. The chemical mine of claim 1 wherein said additive is selected fromthe group consisting of lithium chloride, calcium chloride, magnesiumchloride, sodium sulfate, sodium hydroxide and potassium hydroxide.

3. The chemical mine of claim 2 wherein said additive is calciumchloride.

4. The chemical mine of claim 2 wherein said additive is magnesiumchloride.

5. The chemical mine of claim 2 wherein said additive is sodium sulfate.

6. The chemical mine of claim 2 wherein said additive is sodiumhydroxide.

7. The chemical mine of claim 2 wherein said additive is lithiumchloride.

8. The chemical mine of claim 7, wherein ethylene diamine tetra-aceticacid tetrasodium salt is incorporated.

9. The chemical mine of claim 8 wherein said lithium chloride is presentin an amount of between about 63.2 and 69.2 percent and said tetrasodiumsalt of ethylenediamine tetraacetic acid is present in an amount betweenabout 30.1 and 36.1 percent, both in combination with up to about 0.7percent graphite, all said percentages being by weight.

10. The chemical mine of claim 9 wherein said lithium chloride ispresent in an amount of about 66.2 percent, and said tetrasodium salt ofethylenediamine tetraacetic acid is present in an amount of about 33.1percent, and said graphite is present in an amount of about 0.7 percent.

11. The chemical mine of claim 1, wherein the primary explosive is leadazide.

12. A pellet for use in the sterilization of a chemical mine containinglithium chloride in an amount between about 63.2 and 69.2 percent andthe tetrasodium salt of ethylenediamine tetraacetic acid in an amountbetween about 30.1 and 36.1 percent, and up to about 0.7 percentgraphite, all said percentages being by weight.

13. The pellet of claim 12 wherein the total weight represents about66.2 percent lithium chloride, about 33.1 percent tetrasodium salt ofethylenediamine tetraacetic acid and about 0.7 percent graphite.

References Cited UNITED STATES PATENTS 2,292,956 8/ 1942 McNutt et al149-24 X 2,352,964 6/1944 McNutt et al. 149-24X 2,405,189 8/1946 Clark149-24 X 3,171,716 3/1965 Diekmann et al. 149-2 X 3,368,929 2/1968 Bell149-46 OTHER REFERENCES Uses and Applications of Chemicals and RelatedMaterials, Gregory, Thomas C., vol. I, Reinhold Publishing Corp., NewYork, N.Y., 1939, pp. 137, 354, 539 and 558.

Ibid, vol. II, p. 191.

CARL D. QUARFORTH, Primary Examiner P. A. NELSON, Assistant ExaminerU.S. Cl. X.R.

